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United States Patent | 5,162,708 |
Naito ,   et al. | November 10, 1992 |
A method for driving a supersonic motor includes the steps of driving the supersonic motor by supplying a driving voltage of greater frequency than a resonant frequency (point) to a driving piezoelectric electric element. The driving frequency is decreased when a wave form distortion is not generated in an output signal of an oscillation detection piezoelectric element provided in an elastic body. The driving frequency is increased when a wave form distortion is generated in the output signal of the oscillation detection piezoelectric element.
Inventors: | Naito; Masafumi (Toyohashi, JP); Adachi; Yoshihiro (Hamakita, JP); Kawai; Hironobu (Toyohashi, JP) |
Assignee: | Asmo Co., Ltd (Kosai, JP) |
Appl. No.: | 562031 |
Filed: | August 2, 1990 |
Aug 03, 1989[JP] | 1-201756 |
Current U.S. Class: | 318/116; 310/316.02 |
Intern'l Class: | H01L 041/08 |
Field of Search: | 318/114,116,118,138 310/313 B,316,315,317,319,323,328,318 |
3582733 | Jun., 1971 | Brubaker | 318/116. |
3619757 | Nov., 1971 | Ioerger | 318/138. |
4056761 | Nov., 1977 | Jacoby et al. | 318/116. |
4249100 | Feb., 1981 | Vasiliev et al. | 310/316. |
4403176 | Sep., 1983 | Cranston | 318/114. |
4445063 | Apr., 1984 | Smith | 310/316. |
4630135 | Dec., 1986 | Sato | 310/313. |
4811835 | Mar., 1989 | Bullivant et al. | 318/114. |
4868445 | Sep., 1989 | Wand | 310/316. |
4954741 | Sep., 1990 | Furutsu et al. | 310/317. |
Foreign Patent Documents | |||
62-85684 | Apr., 1987 | JP. | |
62-92781 | Apr., 1987 | JP. | |
62-203575 | Sep., 1987 | JP. |